Carpal boss: effect of wedge excision depth on third carpometacarpal joint stability.

PURPOSE: We hypothesize that carpal-metacarpal (CMC) instability after carpal boss wedge excision is not caused only by damage to the dorsal ligament but mainly depends on the depth of the bony resection. METHODS: To test our hypothesis, this study analyzes the effect of wedge excisions with different depths (0, 15%, 35%, 55% of the third CMC joint) and the effect of different forces (0, 50, 100 N.m) on the stability (measured as the passive flexion) of the third CMC joint using 12 fresh-frozen human cadaver wrists. The passive flexion is defined as the increase in angular motion of the third CMC joint and represents change in stability during flexion of the joint. RESULTS: The results show that the mean passive flexion measured in the wedge excisions of 15% and 35% of the joint did not differ from that of neutral controls. Joints analyzed after a 55% wedge excision showed a significant increase in angular motion (increased passive flexion). This relates to the 50 N.m as well as the 100 N.m loaded test position. CONCLUSIONS: This study shows that a wedge excision of clinically applicable depth of 35% does not create instability during flexion of the third CMC joint when loaded with physiologically relevant forces. Yet an extended and hardly clinically relevant 55% wedge excision results in a change in stability of the joint. To prevent instability when performing a wedge excision for symptomatic carpal boss, care must be taken to avoid excisions that exceed 35% of the third CMC joint.

Vascular anatomy of the hamster retractor muscle with regard to its microvascular transfer.

BACKGROUND: The hamster retractor muscle (RET) is used as an in vivo model in studies of skeletal muscle ischemia-reperfusion injury. The RET is unique in that the muscle can be isolated while preserving the primary vascular supply so that its contractile function can be measured simultaneously with local microvascular responses to experimental interventions. The goal of this study was to understand the anatomical origin of the vascular supply to the RET and determine whether the RET can be used as a free flap after surgical isolation of the thoracodorsal vessels. METHODS: Microdissection was performed to determine the anatomy of the vasculature that supplies and drains the RET. RESULTS: Distinct numbers and patterns of feed arteries (2-4) and collecting veins (1-3) were identified (n = 26 animals). Dye injection (n = 8) of the thoracodorsal artery demonstrated that the RET remains perfused following its isolation on the thoracodorsal pedicle. Heterotopic allograft transplantation of the RET (n = 2) was performed by anastomosing the thoracodorsal vessels to the femoral vessels using the end-to-side technique. CONCLUSIONS: The anatomical relationships indicate that the RET can be used as a free flap model for evaluating the effect of preservation strategies and transplantation on skeletal muscle microcirculation and contractile function.